Transparent or translucent architectural panels usually lose a large amount of the useful thermal and electromangetic energy in a dwelling. The opaque exteriors of buildings by comparison are usually far more insulating. Nonetheless, transparent or translucent panels are employed because they provide light and/or solar energy to a dwelling's interior or indirectly via solar collectors.
Translucent or transparent exterior surfaces which are inexpensive, good insulators would make energy self-sufficient architecture much easier. Glass and steel skyscrapers would have a cost-effective answer to the high fuel costs inherent in poorly insulating glazings. Solar greenhouses and various passive solar designs would no longer lose large amounts of heat at night or require night curtains. The efficiency of packaged solar collector units could be improved and the dangers of nighttime freeze-up minimized.
It is common knowledge that multiple glazings can be used to improve the insulating characteristics of translucent or transparent surfaces. Indeed an insulating panel can be made out of any sheets or membranes by layering the sheets or membranes so that they trap dead air spaces between them. The more dead air spaces, the greater the insulating value. A rule of thumb is that a 2 centimeter thick dead air space between two uninsulating air barriers yields an R-value of roughly 1. The air does the insulating, not the membranes, glazings or sheets.
Within these "dead" air spaces, convection currents are created which bring the air down the relatively cold air barrier and up the relatively hot air barrier. For this reason, beyond a certain point, little improvement in the insulating value is gained by increasing the distance between the air barriers; the convection current will render them all roughly equivalent. Thus, it is really the number of air barriers which is key to the heat insulating capabilities of a multiple air barrier or multiple membrane building panel.
Heretofore, the cost of manufacturing multiple glazed transparent or translucent panels has virtually prohibited using more then two or three glazings. Similarly, opaque insulation using multiple parallel dead air spaces has never been cost-effective.
Membranes can be made to absorb specific sound frequencies by tensioning them to oscillate and dampen specific sound waves. By tensioning many different membranes to absorb different sound frequencies, and combining these membranes into one building panel, a building panel which insulates over a whole spectrum of sound will result. Heretofore, sound insulation comprised of multiple, frequency-specific membranes, has been relatively complex in design and costly to manufacture.
In summary, the use of multiple membranes with interposed dead air spaces can be used both as a technique for thermal insulation and sound insulation. Heretofore, because of the costs of manufacturing panels with multiple parallel air spaces, different means of thermal insulation are usually used. The exceptions to this are transparent or translucent panels where two or three parallel surfaces are frequently employed for improved insulation. If it were not prohibitively expensive, more parallel surfaces would be used so that these transparent or translucent surfaces would insulate better. Similarly, multiple sound-specific tensioned paralled membranes have long offered the capability of serving as sound insulation, but manufacturing costs have been prohibitive.